In wireless communications, spectral resources are shared among wireless communications devices communicating with other devices potentially at the same time. To minimise radio interference, a wireless communications device may be prevented from transmitting in a particular frequency channel if transmission by another wireless communications device in the same frequency channel is detected to be currently taking place. One such scheme to minimise interference is known as dynamic frequency selection, in which a wireless device is configured to detect wireless transmission protected from interference.
Further, wireless signals of different communications protocols can be standardised for transmission in the same or overlapping frequency bands. For example, the emerging IEEE 802.11ac protocol for wireless local area networking and the IEEE 802.11p protocol for vehicular environments are both designed to operate in a radio spectrum near the 5 GHz frequency bands. However, wireless communications devices designed to operate according to one protocol may not necessarily be sensitive to wireless signals of another protocol. Even if a device is designed to operate according to multiple protocols, it may be necessary to switch operation between the multiple protocols to detect presence of signal transmission in a particular protocol. Switching between protocols however leads to a blackout period in which the device is sensitive only to signal transmission in one protocol and becomes unable to detect signals of any other protocols at any one time.
It would therefore be beneficial if a wireless communications device is able to detect presence of any concurrent signal transmission in a protocol other than the protocol in which the device is designed to communicate, while maintaining uninterrupted operation in the protocol for which the device is designed.
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